Clinical trials are research studies involving people to evaluate new treatments, drugs, and prevention methods, divided into phases and types. The U.S. National Institutes of Health categorizes trials into five main types: prevention, screening, diagnostic, treatment, and supportive care trials, each with specific goals and methodologies. Additionally, trials can be classified based on modifications during the study, being either fixed or adaptive.

1. Types Of Clinical Trials And
Its Significance
Types Of Clinical Trials And Its Significance Clinical trials means medical research
studies involving people. They are divided into different stages, called phases. The
earliest phase trials might focus at whether a drug is safe or the side effects it
causes. A later phase trial aims to test and compare whether a new treatment is
better than existing ones.also checkwhy clinical trials are important in clinical
research.
Types of Classifications:
In one way of classification it is based on the behavior of researches:

2. • Clinical observational study: The investigators observe the
subjects and measure their outcomes. They don’t actively manage the
study.
• Intervention study: The investigators give the research subjects a
particular medicine to compare the treated subjects with those
receiving no treatment or the standard treatment. Based on
inferences the investigator measures the health changes if any.
The U.S. National Institutes of Health (NIH) organizes trials into five
different types:
• Prevention trials : It attempts to find better ways to prevent
diseases in people who were never susceptible or to prevent a disease
from returning. These approaches include medicines, vitamins,
vaccines, minerals, or lifestyle changes.An example of a
prevention trial is the IBIS 2 breast cancer prevention trial.
• Screening trials: The best way to detect certain diseases or health
conditions. The study of causes and patterns of disease is called
epidemiology. Most epidemiological studies are observational
studies.There are three types of observational studies
– cohort studies,case control studies and cross sectional
studies.

3. • Diagnostic trials : To find better alternative for diagnosing a
particular disease or condition. For example to study tests or
procedures that could be used to identify cancer more accurately.
Diagnostic trials usually include people who have signs or symptoms
of the disease.
• Treatment trials : It efforts testing experimental treatments, new
combinations of drugs, or new approaches to surgery or radiation
therapy. They are conducted with diseased people as test subject.
They aim answering specific questions about and evaluate the
effectiveness of a new treatment or a new drug or a new approach of
using a standard treatment.
• Supportive care trials : It attempts find the quality of trials. It aims
finding ways to improve the comfort and quality of life for individuals
with a chronic illness.
• Expanded access trials : Also known as compassionate use trials. It
provides partially tested, unapproved therapeutics to a small number
of patients who have lost all realistic options. Usually this involves
disease for which no effective therapy has been yet approved.
A third classification is whether the trial design allows changes based
on data accumulated during the trial.
• Fixed trials : It considers existing data only during the trial’s design,
and does not modify the trial after it begins and even not assess the
results until the study is complete.

4. • Adaptive clinical trials: This use existing data to design the trial and
then use inferred results to modify the trials as it proceeds.
Modifications include dosage, sample size, drug undergoing trial,
patient selection criteria and “cocktail” mix. Adaptive trials often
employ a Bayesian experimental design to assess the trial’s progress.